In his freshman season of 2003–04, Hunwick finished third among team defenseman in scoring with 15 points in 41 games and was named to the CCHA All-Rookie Team as the Wolverines progressed to the North-East regional finals.[2] Hunwick was then selected at the conclusion of the season by the Boston Bruins, in the seventh round, 224th overall, of the 2004 NHL Entry Draft.

As a sophomore in the 2004–05 season he scored his first career hat-trick, in a 8-3 victory over Bowling Green State on December 10, and was honored as the NCAA National Offensive player of the week.[3] Hunwick increased his points total to 25 in 40 games with the Wolverines to be named to the CCHA Second All-Star Team. Hunwick received the same Second All-Star accolade while serving as an alternate captain in 2005–06, when he recorded a personal best 11 goals and 30 points in 41 games to finish second among Wolverines D-men.[4]

Returning as a senior to the Michigan Wolverines in the 2006–07 season, Hunwick took over as team captain.[5] He was apart of a formidable blueline partnership alongside Jack Johnson, while recording a career high 21 assists and posting 27 points in 41 games. Awarded the Wolverines’ Vic Heyliger Trophy as the team’s most outstanding defenseman for a third consecutive season, Hunwick was named to the CCHA First All-Star Team, West Second All-American Team and given the honour as the CCHA's best defensive defenseman.[6]

Following completion of his collegiate career, Hunwick was then signed by the Boston Bruins to a two-year entry level contract on June 26, 2007.[7] Attending his first Bruins training camp, Hunwick was among the final cuts and assigned to American Hockey League affiliate, the Providence Bruins to begin the 2007–08 season.[8] After spending a month with Providence, Hunwick was recalled by Boston and played his first NHL regular season game in a 2-1 victory over the Buffalo Sabres on November 10, 2007. In his third recall to the Bruins, Hunwick recored his first NHL point, an assist in a 2-1 defeat of the Toronto Maple Leafs on December 9, 2007.[9] He finished his first professional season, primarily with Providence scoring 23 points in 55 games while totaling 13 games in the NHL from four separate recalls.

In the following 2008–09 season, Hunwick was again initially re-assigned to the AHL but after only 2 games was recalled and remained with the Bruins for the majority of the campaign. He scored his first career goal against Vesa Toskala in a 3-2 win over the Toronto Maple Leafs on November 17, 2008.[10] His goal sparked a 6 game scoring streak which tied Hall of Fame defenseman, Ray Bourque, as a club record for rookie defenseman. On January 10, 2009, in a game against the Carolina Hurricanes, Hunwick got into his first NHL fight, one-punching to knock down Justin Williams.[11] Establishing a puck-moving role among the Bruins defense corps, Hunwick amassed a career high 21 assists and 27 points in 53 regular season games. Hunwick made his post-season debut with the Bruins in game one of the Eastern Conference Quarterfinals against the Montreal Canadiens on April 16, 2009. However on April 18, 2009, at a team meeting before game two against the Canadiens, Hunwick complained of abdominal pain. After consultation with the team doctor, it was determined that he needed medical treatment and Hunwick was taken to the hospital via ambulance. He underwent emergency surgery for a ruptured spleen, and was ruled out for the remainder of the playoffs.[12]

Hunwick opted out of salary arbitration and re-signed to a two-year contract with the Bruins on July 20, 2009.[13] Recovered from his splenectomy, Hunwick played his first full NHL season in 2009–10, playing in a career high 76 games. Despite matching his 6 goals from the previous year, Hunwick regressed offensively and struggled to recapture his form throughout the year to be occasionally relegated as a reserve defenseman. He recorded an assist as his first career post-season point in game one of a series Quarterfinals victory against the Buffalo Sabres.[14] Succumbing to the Philadelphia Flyers in the Eastern Conference Semi-finals, Hunwick finished to appear in all 13 playoff games for 6 assists.

In the 2010–11 season, with the Bruins in need to reduce roster salary, Hunwick was traded to the Colorado Avalanche in exchange for Colby Cohen on November 29, 2010.[15] On November 30, 2010, Hunwick made his debut for the Avalanche in a 3-2 overtime defeat.[16]